Network with an illegal topology | 3Com 9100 specs

88CHAPTER 6: SPANNING TREE PROTOCOL (STP)

Figure 13 Network with an illegal topology

This configuration is illegal because it creates loops that cause the network to overload. However, STP allows you to use this configuration because STP detects duplicate paths and immediately prevents (or blocks) one of them from forwarding traffic.

Figure 14 shows an example of enabling STP on the bridges in the configuration. The STP system has decided that traffic from LAN segment 2 to LAN segment 1 can only flow through Bridges C and A.

Figure 14 Traffic flowing through Bridges C and A

Image 88

3Com 9100 manual Network with an illegal topology

Contents

SuperStack Switch User Guide 3Com Corporation 5400 Bayfront Plaza Santa Clara, California Contents Installation and Setup Virtual Lans Vlans Forwarding Database FDB Quality of Service QOS Using the WEB Interface Technical Specifications Troubleshooting Page Ethernet concepts Ethernet switching and bridging concepts About this Guide Conventions Icon DescriptionConvention Description Screen displays Related DocumentationYear Compliance About this Guide Switch 9100 Overview SwitchFeatures About Simple Network Management Protocol Snmp For information on load sharing, refer to Chapter Virtual LANs VLANs Configuration Quality of Service QoSNetwork Example Switch 9100 used in a backbone configuration Key View Front panel has the following featuresPorts Describes the LED behavior on the Switch LEDsStandard Media Type Mhz/Km Rating Maximum Distance Color Indicates 1000BASE-SX Port Status LEDs Color Indicates 100/1000BASE-TX Port Status LEDs Switch 9100 Rear shows the Switch 9100 rear viewUnit Status LED Power Sockets Reset ButtonSerial Number MAC Address Public Determining Installation and SetupLocation Tabletop InstallingRack Mounting Installing the Switch 9100 Connecting Equipment to the Console Port Function Pin Number Direction Switch Installation Flashes until the switch has successfully passed the Post Default Vlan named default Login adminLogging on for First Time Installation and Setup Accessing the Switch Accessing the Switch You could enter the following shortcut Be a range of numbers, for example Symbol Description Config vlan name ipaddress ipaddressConfig snmp community readonly readwrite string Reboot date time cancel Create account admin user username encrypted password Line-Editing Keys Command Description Disable bootp vlan name all Disable cli-config-loggingDisable clipaging Disable idletimeout Configuring Management Access Unconfig switch allShow banner 3C177052 Account Name Access Level Changing the Default Password3C1770519# Viewing Accounts Create account admin user username encryptedShow accounts Methods Managing Switch Using AccessProfiles Deleting an Account Config access-profile accessprofile Access Profile Example To view the contents of an access profile, type Using Telnet To view the Telnet configuration, typeConnecting to Another Host Using Telnet Using a Bootp Server Manually Configuring the IP Settings Config vlan name ipaddress ipaddress subnetmask Config iproute add default ipaddress metricFor example Your changes take effect immediately Show session Terminate the session by using the following commandClear session sessionnumber Commands Using the WebOn the switch IP Host Using Snmp Accessing SwitchAgents Supported MIBs Enable Snmp access Enable Snmp traps Command Ping command syntax is Options for the ping command are described in TableChecking Basic Connectivity Switch 9100 Ports Configuring Switch Port Speed Duplex SettingEnabling Disabling Enable learning ports portlist Enable ports portlistEnable sharing masterport Config ports portlist qosprofile Disable learning ports portlist Disable ports portlistDisable sharing masterport Show ports portlist txerrors Accessing the Switch Enable sharing 4 grouping Configuration Port-MirroringVerifying the Load Sharing Commands Disable mirroringExample Show mirroring Accessing the Switch VLANs help to control traffic VLANs provide extra security VLANs ease the change and movement of devices Igmp OverviewIgmp Snooping Enable igmp snooping Enable igmp vlan nameForward-mcrouter-only Forward-mcrouter-only is specified, Types of VLANs Port-Based VLANs Spanning Switches with Port-Based VLANs Marketing Finance Sales Switch AccountingEngineering Uses of Tagged VLANs Assigning a Vlan Tag Shows a logical diagram of the same network Tagged Ports Mixing Port-Based and Tagged VLANs Following protocol filters are predefined on the switch NetBIOS DECNet IPX8022Predefined Protocol Filters AppleTalk Defining Protocol Filters Config protocol protocolname add protocoltype HexvalueCreate protocol protocolname Deleting a Protocol Filter Vlan NamesPackets Over Protocol Configuring VLANs On the Switch 6 to it To display Vlan settings, use the following command Displaying Vlan SettingsShow vlan name Deleting VLANs Virtual Lans Vlans Forwarding Database FDB Associating a QoS Profile with an FDB Entry Config fdb agingtime number Disable learning portsEntries Following example adds a permanent entry to the FDB Displaying FDB Entries To display FDB entries, use the commandShow fdb macaddress vlan name portlist Permanent Delete Fdbentry macaddress vlan Removing FDBName Clear fdb macaddress vlan name portlist Forwarding Database FDB Spanning Tree Protocol STP OverviewSpanning Tree Protocol Network with an illegal topology Initialization Traffic flowing through Bridge B Domains ReconfigurationStabilization STPD2 contains VLANs Manufacturing and Engineering Stpd Marketing & Sales Marketing, Sales & Engineering Configuring STP on the Switch Config stpd stpdname add vlan nameEnable stpd stpdname Create stpd stpdname Shows the commands used to configure STP Enable stpd port portlist Displaying STP SettingsThrough 3, and port Resetting STP Listed in Table Spanning Tree Protocol STP Quality of Service Quality of Service QOSBuilding Blocks QoS Profiles Profile Name Priority Minimum Bandwidth Maximum Bandwidth Vlan Permanent MAC addresses Dynamic MAC Addresses Command to clear the FDB is as follows Verifying MAC-Based QoS SettingsOr the command Blackhole Config dot1p type dot1pvalue qosprofile qosname Enable dot1p replacement ports portlist all802.1p Packets Physical and Logical Groupings Source Port Verifying Physical and Logical Groupings Displaying QoS Information QoS Monitor Verifying Configuration PerformanceShow ports portlist qosmonitor Enable qosmonitor port port Disable qosmonitor Configuring QoS Quality of Service QOS Status Monitoring Statistics Show log config Show switchShow log priority Show memory Port Statistics To view port statistics, use the following commandAccuracy To view port transmit errors, use the following command Port ErrorsTo view port receive errors, use the following command Display Keys Port MonitoringLogging Is specific to the problem Where the following is trueLevel Description Clear log static Configure remote logging by using the following command To configure the log display, use the following commandReal-Time Display Disable log display Disable syslog Rmon features supported by the switch On the networkAllows you to monitor LANs remotely Clear Counters Statistics AlarmsHistory Events Improving EfficiencyAllowing Proactive Management Reducing the Traffic Load Rmon Group Support Supplied by the Switch Statistics AlarmsHistory Events Enable disable rmon Action High Threshold Status Monitoring and Statistics Enabling Disabling Web Access Using the WEB InterfaceTo re-enable Web access, use the following command Accessing the Web Setting Up YourBrowser Task Frame Navigating the Web InterfaceWebserver busy Status Messages Browser ControlsSelection Type Key Sequence Saving Changes Configuring a VlanDo a Get When Using the WEB Interface Software Upgrade and Boot Options Secondary image and configuration file on the switchDownloading a New Image Saving Rebooting the SwitchChanges Upgrading Software Upgrade and Boot Options Boot Option Show configurationCancel option Save configuration primary Software Upgrade and Boot Options Safety Information Important Safety Information Lithium Battery Appendix a Safety Information ’information de Sécurité Importante Appendix a Safety Information Batterie au lithium Wichtige Sicherheitsinformat ionen Europe Warnung Faseroptikanschlüsse Optische Sicherheit Lithiumbatterie Appendix a Safety Information Technical Specifications Protocols Used for Administration Terminal Emulation Troubleshooting LEDs Using Command-Line Interface Switch does not power upSnmp Network Manager cannot access the device Telnet workstation cannot access the device Traps are not received by the Snmp Network Manager Permanent entries remain in the FDB Port Configuration No link light on 100/1000BASE-TX port You forget your password and cannot logExcessive RX CRC errors No link light on Gigabit fiber port VLANs You cannot add a port to a Vlan Vlan names VLANs, IP Addresses and default routes802.1Q links do not work correctly Using the Command-Line Interface Appendix C Troubleshooting Technical Support ServicesOnline Technical Access by Analog Modem Username anonymousHours a day, 7 days a week Country Data Rate Telephone Number 847 262 Access by Digital Modem408 727 Europe, South Africa, and Middle East Country Telephone Number Asia, Pacific Rim Country Telephone Number Fax Number Page Glossary Bridge BroadcastBroadcast storm Collision Glossary IP address LatencyLine speed Loop Port trunks See load sharing Repeater Resilient linkRouter Segment Switch Switch DatabaseStandby port Telnet Glossary Index AdminNumbers FDB Rmon Tftp Index Index Index of Commands 118 Index of Commands Index of Commands 3Com Corporation Limited Warranty Warranties Exclusive Governing LAW EMC Statements